/*
 * 拖拽指令
 */
export default {
    inserted(el) { // 这里的el是标签中的v-drag
        let positionParams = {
            x: 20,
            y: 105,
            startX: 0,
            startY: 0,
            endX: 0,
            endY: 0
        }
        el.addEventListener('touchstart', function (e) {
            positionParams.startX = e.touches[0].pageX
            positionParams.startY = e.touches[0].pageY
        })
        el.addEventListener('touchend', function (e) {
            positionParams.x = positionParams.endX
            positionParams.y = positionParams.endY
            positionParams.startX = 0
            positionParams.startY = 0
        })
        el.addEventListener('touchmove', function (e) {
            if (e.touches.length > 0) {
                let offsetX = e.touches[0].pageX - positionParams.startX
                let offsetY = e.touches[0].pageY - positionParams.startY
                let x = positionParams.x - offsetX
                let y = positionParams.y - offsetY
                if (x + el.offsetWidth > document.documentElement.offsetWidth) {
                    x = document.documentElement.offsetWidth - el.offsetWidth
                }
                if (y + el.offsetHeight > document.documentElement.offsetHeight) {
                    y = document.documentElement.offsetHeight - el.offsetHeight
                }
                if (x < 0) { x = 0 }
                if (y < 0) { y = 0 }
                el.style.right = x + 'px'
                el.style.bottom = y + 'px'
                positionParams.endX = x
                positionParams.endY = y
                e.preventDefault()
            }
        })
    }
}